Ahlmark, Daniel Innala

Abstract [en]

For millions of visually impaired individuals worldwide, independent navigation is a major challenge. The white cane can be used to avoid obstacles close-by, but it does not aid in navigation as it is difficult to get a large-scale view of the environment. Technological aids have been developed, notably ones based on GPS, but they have not been widely adopted. This thesis approaches the problem from different perspectives. Firstly, current navigation aids are examined from a user-interaction perspective, leading to some design guidelines on how to present spatial information non-visually. Secondly, a prototype of a new navigation aid (the Virtual White Cane) is proposed, and a field trial with visually impaired participants is described. The idea behind the Virtual White Cane is to utilise the intuitive way humans avoid obstacles by touch, and specifically to leverage the experience white cane users already have. This is accomplished by scanning the environment with a laser rangefinder, and presenting the range information using a haptic interface. The regular white cane is easy to use because it behaves like an extended arm, and so does the Virtual White Cane, albeit working at a much greater distance than the regular cane. A field trial with six experienced white cane users was conducted to assess the feasibility of this kind of interaction. The participants carried out a trial procedure where they traversed a prepared environment using the Virtual White Cane. They did not receive extensive training prior to the trial, the point being that if the Virtual White Cane behaves like a regular one, it should be quick to learn for a white cane user. The results show that spatial information can be feasibly conveyed using a haptic interface. This is demonstrated by the ease with which the field trial participants familiarised themselves with the system, notably adopting a similar usage pattern. In interviews that were conducted following the trial procedures, the participants expressed interest in the idea and thought that being a white cane user helped them use the Virtual White Cane. Despite knowing how to operate the system, the participants found locating objects to be difficult. An extended training period would likely have made this easier, but this problem could also be lessened by understanding what model parameters (such as the length of the virtual cane) should be used.